dt-bindings: gpio: simplify GPIO hog nodes schema

The core schema in dtschema already strictly defines contents of nodes
with "gpio-hog" property (with additionalProperties: false), thus the
only thing device schema should do is: define "type: object" and
required "gpio-hog".  Make the code a bit simpler by removing redundant
parts.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240828-dt-bindings-gpio-hog-v1-3-63b83e47d804@linaro.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>